Scanning lens unit and optical scanning apparatus including the same

摘要

The scanning lens unit includes lenses located between a optical deflector and a lens having a k-th lens surface S k from a first lens surface S 1 closest to the deflector are disposed such that a height of a lens having the lens surface S k denoted by   k satisfies the predetermined expression. Each of lenses located between the first lens surface S 1 and the k-th lens surface S k is a cylindrical lens having power only in the determined deflection direction. Therefore, the lenses can individually have minimum thicknesses, as a result, the cost reduction of the scanning lens unit is realized. The optical scanning apparatus includes the scanning lens and hence can achieve cost reduction.